Which technique automatically limits VLAN traffic to only the switches that require it?

A.

access lists

B.

DTP in nonegotiate

C.

VTP pruning

D.

PBR

Correct Answer:C

Explanation:

VTP pruning enhances network bandwidth use by reducing unnecessary flooded traffic, such as broadcast, multicast, unknown, and flooded unicast packets to only the switches that require it. VTP pruning increases available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to access the appropriate network devices. By default, VTP pruning is disabled.

Which statement describes what happens when a switch enters dual active recovery mode?

A.

The switch shuts down and waits for the VSL link to be restored before sending traffic.

B.

All interfaces are shut down in the formerly active virtual switch member, but the new active virtual switch forwards traffic on all links.

C.

The switch continues to forward traffic out all links and enables spanning tree on VSL link and all other links to prevent loops.

D.

The VSS detects which system was last in active state and shuts down the other switch.

Correct Answer:B

Explanation:

In the dual active recovery mode, all interfaces except the VSL interfaces are in an operationally shut down state in the formerly active virtual switch member. The new active virtual switch continues to forward traffic on all links. Reference:http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/prod_qas0900aecd806ed74b.html

QUESTION 24

A network engineer must improve bandwidth and resource utilization on the switches by stopping the inefficient flooding of frames on trunk ports where the frames are not needed. Which Cisco IOS feature can be used to achieve this task?

A.

VTP pruning

B.

access list

C.

switchport trunk allowed VLAN

D.

VLAN access-map

Correct Answer:A

Explanation:

Cisco advocates the benefits of pruning VLANs in order to reduce unnecessary frame flooding. The”vtp pruning”command prunes VLANs automatically, which stops the inefficient flooding of frames where they are not needed.

Pilot testing of the new switching infrastructure finds that when the root port is lost, STP immediately replaces the root port with an alternative root port. Which spanning-tree technology is used to accomplish backup root port selection?

A.

PVST+

B.

PortFast

C.

BackboneFast

D.

UplinkFast

E.

Loop Guard

F.

UDLD

Correct Answer:D

Explanation:

If a switch loses connectivity, it begins using the alternate paths as soon as the spanning tree selects a new root port. By enabling UplinkFast with the spanning-tree uplinkfast global configuration command, you can accelerate the choice of a new root port when a link or switch fails or when the spanning tree reconfigures itself. The root port transitions to the forwarding state immediately without going through the listening and learning states, as it would with the normal spanning-tree procedures.

UplinkFast provides fast convergence after a direct link failure and achieves load balancing between redundant Layer 2 links using uplink groups. An uplink group is a set of Layer 2 interfaces (per VLAN), only one of which is forwarding at any given time. Specifically, an uplink group consists of the root port (which is forwarding) and a set of blocked ports, except for self-looping ports. The uplink group provides an alternate path in case the currently forwarding link fails.

A network engineer is setting up a new switched network. The network is expected to grow and add many new VLANs in the future. Which Spanning Tree Protocol should be used to reduce switch resources and managerial burdens that are associated with multiple spanning-tree instances?

A.

RSTP

B.

PVST

C.

MST

D.

PVST+

E.

RPVST+

Correct Answer:C

Explanation:

Multiple Spanning Tree (MST) extends the IEEE 802.1w RST algorithm to multiple spanning trees. The main purpose of MST is to reduce the total number of spanning-tree instances to match the physical topology of the network and thus reduce the CPU cycles of a switch. PVRST+ runs STP instances for each VLAN and does not take into consideration the physical topology that might not require many different STP topologies. MST, on the other hand, uses a minimum number of STP instances to match the number of physical topologies present.

Figure 3-15 shows a common network design, featuring an access Switch A, connected to two Building Distribution submodule Switches D1 and D2. In this setup, there are 1000 VLANs, and the network administrator typically seeks to achieve load balancing on the access switch uplinks based on even or odd VLANs–or any other scheme deemed appropriate.

Figure 3-15: VLAN Load Balancing

Figure 3-15 illustrates two links and 1000 VLANs. The 1000 VLANs map to two MST instances. Rather than maintaining 1000 spanning trees, each switch needs to maintain only two spanning trees, reducing the need for switch resources. Reference: http://ciscodocuments.blogspot.com/2011/05/chapter-03-implementing- spanning-tree_19.html

QUESTION 27

Refer to the exhibit. A multilayer switch has been configured to send and receive encapsulated and tagged frames. VLAN 2013 on the multilayer switch is configured as the native VLAN. Which option is the cause of the spanning-tree error?

A.

VLAN spanning-tree in SW-2 is configured.

B.

spanning-tree bpdu-filter is enabled.

C.

802.1q trunks are on both sides, both with native VLAN mismatch.

D.

VLAN ID 1 should not be used for management traffic because its unsafe.

Correct Answer:C

Explanation:

Here we see that the native VLAN has been configured as 2013 on one switch, but 1 (the default native VLAN) on the other switch. If you use 802.1Q trunks, you must ensure that you choose a common native VLAN for each port in the trunk. Failure to do this causes Cisco switches to partially shut down the trunk port because having mismatched native VLANs can result in spanning-tree loops. Native VLAN mismatches are detected via spanning tree and Cisco Discovery Protocol (CDP), not via DTP messages. If spanning tree detects a native VLAN mismatch, spanning tree blocks local native VLAN traffic and the remote switch native VLAN traffic on the trunk; however, the trunk still remains up for other VLANs.

A network engineer configured a fault-tolerance link on Gigabit Ethernet links G0/1, G0/2, G0/3, and G0/4 between two switches using Ethernet port-channel. Which action allows interface G0/1 to always actively forward traffic in the port-channel?

A.

Configure G0/1 as half duplex and G0/2 as full duplex.

B.

Configure LACP port-priority on G0/1 to 1.

C.

Configure LACP port-priority on G0/1 to 65535.

D.

LACP traffic goes through G0/4 because it is the highest interface ID.

Correct Answer:B

Explanation:

A LACP port priority is configured on each port using LACP. The port priority can be configured automatically or through the CLI. LACP uses the port priority with the port number to form the port identifier. The port priority determines which ports should be put in standby mode whenthere is a hardware limitation that prevents all compatible ports from aggregating. The higher the number, the lower the priority. The valid range is from 1 to 65535. The default is 32768.

You have been asked to install and configure a new switch in a customer network. Use the console access to the existing and new switches to configure and verify correct device configuration.

Refer to the configuration. For which configured VLAN are untagged frames sent over trunk between SW1 and SW2?

A.

VLAN1

B.

VLAN 99

C.

VLAN 999

D.

VLAN 40

E.

VLAN 50

F.

VLAN 200

G.

VLAN 300

Correct Answer:B

Explanation:

The native VLAN is used for untagged frames sent along a trunk. By issuing the “show interface trunk” command on SW1 and SW2 we see the native VLAN is 99.

QUESTION 30

A network engineer tries to configure storm control on an EtherChannel bundle. What is the result of the configuration?

A.

The storm control settings will appear on the EtherChannel, but not on the associated physical ports.

B.

The configuration will be rejected because storm control is not supported for EtherChannel.

C.

The storm control configuration will be accepted, but will only be present on the physical interfaces.

D.

The settings will be applied to the EtherChannel bundle and all associated physical interfaces.

Correct Answer:D

Explanation:

After you configure an EtherChannel, any configuration that you apply to the port-channel interface affects the EtherChannel; any configuration that you apply to the physical interfaces affects only the interface where you apply the configuration. Storm Control is an exception to this rule. For example, you cannot configure Storm Control on some of the members of an EtherChannel; Storm Control must be configured on all or none of the ports. If you configure Storm Control on only some of the ports, those ports will be dropped from the EtherChannel interface (put in suspended state). Therefore, you should configure Storm Control at the EtherChannel Interface level, and not at the physical interface level.